Submarine detecting device



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2.434.271: 1 SUBMARINE nn'mc'rmo nevron Warren P. Mason. West Orange, N.J., assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York Application March 4, 1943, Serial No.477,910 Claims. (Cl. 177-386) This invention relates to locating devicesand particularly to that class of devices by which supersonic vibrationsset up by propellers of ships are located in direction.

The principle by which the geopraphical location of a source of sound orvibrations may be fixed is well known. The object of the presentinvention is to provide a portable device which may be temporarily laidon the bed of the ocean and connected to an observation point by asubmarine cable and which will be rugged, accurate and economical.

' In accordance with the invention an array of piezo-electric crystalsin the form of a triangular device each leg of which constitutes a,frequency ,prism is employed. Each of the said legs of the triangleconsists of a plurality of crystals connected in a network to produce aprismatic effect so that by observation an angular determination may bemade from each leg. Two such observations will determine the azimuth andcolatitude angles of the source of vibrations and this may be checked byobservation of the third leg.

It has been known heretofore to use three microphones at the apices of atriangle to make location determinations of foreign disturbances bytrigonometric methods, the plane of the triangle being adjusted until aline normal to the said plane points directly at the source of thedisturbance. In the present case, however, the plane of the triangle isto be adiusted on as nearly a horizontal plane as possible and then leftstationary the determination of the required direction being made as theintersection of two planes, the angle of approach to each of two legsbeing determined by the prismatic character of the crystal arrayand theelectrical networks in which the said two legs are connected. Theadjustment is not made herein by balancing methods as in the prior artbut rather by angular prismatic determination, for a completeunderstanding of which reference is made to my copending applicationsone entitled Pipe antennas and prisms Serial No. 381,236, filed March 1,

1941, Patent 2,408,435, and another entitled "Prismath; and high powercompressional wave radiators and receivers" Serial No. 431,558 filedFebruary 19, 1942, Patent 2,404,391.

A feature of the invention is a triangular device each leg of whichcontains an array of crystals and a circuit network for the directionallocation of a source of vibrations.

Another feature of the invention is a'triangular device each leg ofwhich may be used as an angle detector and in which any two legs willdefinitely determine the direction of a source of vibrations. Where oneleg may be oriented in such a manner that the incoming waves strike atoutside its most sensitive range the other two legs may be used for thetest.

Another feature of the invention is a straight line array-ofpiezoelectric crystals in an electrical network which defines the angleof approach of compressional waves between the locator and the source ofdisturbance as a-function of the frequency detected, said crystal arraybeing rendered more accurate in its response by means in said network torender the said crystals progressively more sensitive from the ends ofsaid array to the middle thereof. For a more complete and detailedexplanation of the phenomenon of the suppression of secondary lobesreference is made to my copending application entitled Radiating systemsSerial No. 407.457, filed August 19. 1941,

now Patent No. 2,411,551 dated November 26, 1946.

The drawings consist of thirteen sheets having sixteen figures, asfollows:

Fig. 1 isa geometrical diagram, being a plan of the intersection of twoplanes which are indicated in perspective and showing the line formed bythe intersection thereof running from a detecting instrument to a sourceof disturbance:

Fig. 2 is a perspective view of the same;

Fig. 3 is another geometrical figure, being a plan of the anglesdetermined by the line from the detecting instrument to the source ofdisturbance;

Fig. 4 is a perspective view of the same;

Fig. 5 is a vertical cross-section of one leg of the triangular prism;

Fig. 6 is a fragmentary, vertical cross-section of the same taken amongthe longitudinal axis thereof;

Fig. 7 is a schematic circuit diagram showing the general layout of thetriangular prism and the circuit connections of the testing meansconnected thereto for determination of the azimuth and 'colatitudeangles of the source of disturb ance;

Fig. 8 is a block diagram showing how the figures on the remainingsheets'may be placed to form a. complete circuit diagram of thearrangement shown schematically in Fig. '7;

Fig. 9 is a circuit diagram showing the circuit arrangement, partly inschematic, of two legs of the triangular prism, and the third leg as ablock;

Fig. 10 shows the input switching circuits and the preliminaryamplifiers:

Fig. 11 shows the output pads, the band-pass filters and the scanningoscillators next in line;

Fig. 12 shows the scanning modulator, the band-pass filters and theintermediate frequency amplifiers next in line;

Fig. 13 shows the buffer amplifiers, the demodulator, the band-passfilters, attenuators and final amplifiers next in line, as well ascertain circuit elements of the alert channel;

Fig. 14 shows 'the output switching circuit whereby the detecting devicemay be alternatively connected to diflerent channels;

Fig. 15 shows circuit details of the power supply: and

Fig. 16 is a cross-sectionalyiew of the construction of the cable bywhich the triangular prism circuit is connected to the detectingcircuits.

In Fig. l a vessel l is shown whose propeller is a source ofdisturbance. Located at some distance therefrom is a triangular prismhaving the three legs A, B and C. This prism will be located in ahorizontal position on the bed of the sea and the vessel will be locatedabove it, either on the surface of the sea or submerged. The problem isto determine the azimuth and colatitude angles of the line extendin fromthe theoretical center of the triangular prism to the source ofdisturbance and this may be done by calculating the intersection of atleast two planes experimentally fixed by the electrical response of thedifferent legs of the prism.

For purposes of illustration, the center of the prism is used as acenter point of a hemisphere, somewhere in whose surface lies the sourceof disturbance. The circle shown by the dot and dash line is thehorizontal trace of the hemisphere in whose plane the triangular prismis located. Two planes, one determined by the leg A and one determinedby the leg B are defined each by a diameter of the said circle and bythe great circle trace of the plane as it cuts the hemisphericalsurface. The plane determined by the leg A is shown by the shadedsurface within the area defined by the horizontal surface straight linea2, a, at, which is normal to the longitudinal axis of the leg A, andthe great circle trace a2, a3, al, which passes through the source ofdisturbance. Likewise, the plane determined by the leg B is shown by theshaded surface within the area defined by the horizontal surfacestraight line M, b, bl, which is normal to the longitudinal axis of theleg B, and the great circle trace b2, b3, bl, which also passes throughthe source of disturbance. The intersection of these two planes is astraight line extending from the source of disturbance to the center ofthe prism.

The plane determined by the leg A may be said to be determined by twostraight lines, one the line a2, a, al, lying in a horizontal plane andat right angles to the longitudinal axis of the leg A, and another a,a3, at right angles to the first line but at a measurable angle to thehorizontal plane. This is known as the angle of approach and is thatangle which the leg A will measure in accordance with the principles setforth in my copending applications, heretofore mentioned. This angle,shown as angle a may be visualized more clearly in perspective of Fig.2. The corresponding angle defining the plane determined by tl21e leg Bmay be even more clearly seen in Fig.

Thus by electrical measurements of the frequency of the incoming wavesfrom the source of disturbance the angles a and s may be determined andthese determine the planes whose intersection is the straight linebetween the center of the triangular prism and the source ofdisturbance.

A third angle which may be termed i may be determined by the leg C andmay be used as a check. Practically the three angles are all measuredand those two which are closest to ninety degrees are selected forusesince the greatest accuracy is attained when the incoming wave is in aplane normal to the longitudinal axis of the prism.

Now considering Figs. 3 and 4, the direction of the source ofdisturbance may be located by calculation. The line from the centerofthe prism to the source of disturbance being known, the azimuth anglemay be calculated. This as seen most clearly from Fig. 3 is the anglefrom a given reference line, here the line from the center of the prismdue north, to the projection on the horizontal plane of the determinedline from the center of the prism to the source of disturbance. Thecolatitude angle may also be calculated. This is the angle between aline from the center of the prism to the zenith and the determined linefrom the center of the prism to the source of disturbance, bestillustrated in Fig. 4.

Thus by the response of the different legs of the prism, first theangles a, ,8 and A are measured. These may be translated by calculation,through the intersection of two planes into the azimuth and coiatitudeangles of the source of disturbance so that by plotting methods thedirection of the source of disturbances may be definitely located inreference to known objects (including the triangular prism) andlandmarks.

The construction and arrangement of the triangular prism is shown inFigs. 5 and 6. One leg of the prism as will appear more fullyhereinafter contains certain apparatus not present in the other legs andit is that leg which is shown. The leg is in the form of a steel tube orshell 2 entirely covered with rubber 3. At the top socalled "windows arecut out so that only the rubber 3 is interposed between the sea water onthe outside and the liquid medium 4 in which all the apparatus on theinside is submerged,

The apparatus consists of piezoelectric crystal units 55 mounted on aplate 6 in cooperative relationship with a lead backing resonator I. Ashort space below the active face of the backing resonator I there islocated a slotted plate 8 which acts as a means to attenuate thevibrations from the active face of the backing resonator in ac--cordance with the principles set forth in my copending application,Serial No. 470,837, filed December 31, 1942, now Patent No, 2,415,832dated Feb. 18, 1947.

There are also a plurality of relays 8, l0, H and I2 mounted on theplate l3 which may be generally of the type shown in Patent 2,303,933granted December 1, 1942, to D. A. S. Hale. These relays will not bepresent in the other two legs of the prism. Below the plate I3 there ismounted a container l4 holding the elements of,

- The operation of the device may be seen from the schematic circuitdiagram of Fig. "l; The triangular prism l isfshown at the, left and itsthree legs are designated AB and C'as-in previous figures; Eachleg isconnected by a two conductor channelto a testing channel and in additionthe leg Als shownas having an extra two conductors extending theretojforswitchin purposes to be morefully described hereinafter, Three testingchannels are provided for individually determining the frequency ofincoming waves. In addition, a fourth testing channel is provided-as anI testing means,- In use the triangular prism isv placed on the bedofthe sea and connected to the testing means either aboard a sta tionaryvessel or in some for on land.- The connection is by means of asubmarine cable shown in cross-section in Fig. 16. The; device isportable I in that, the triangular prism may be hauled up'and relocatedat will and the testing apparatus may be transported to anyotherconvenient location.

By means of theswitching circuits to 20, any one or all of the legs ofthe prism may be connected through the alert channel 2| to the earphones22 or any other, responsive device such as 23 here labeled oscilloscope.Usually by means of switching means within the leg A such the relay legis rendered non-directional in its response to incoming '24, theearphones 22 or the indicator 23 may be individually connected to theleg A of the prism.

housing provided thereas a "visual indicator such as an way ofe'xample.-The-receiver consists" of four channels. One, called the "alertchannel,". is for 1 the purpose of determining the presence of a signalatthe input, while the other three, called scanning channels," are forthe purpose of iden-' tifying the frequency alert channel'consistsplifierswith' attenuators at their inputs and two I filters,.a high-passand a low-pass filter, whose purpose 'is tolim-it the useful frequencyrange to the band extending from- 1 kilo'cycle to 10 kilocycles. A

scanningjchannel 'consistsot a. preamplifier withan attenuator at itsinput, a modulaltorand with an adjustable attenuator at the input of themodulator anda band-pass filter tolimit the received signals to the.band extending from 7,5 kilocycles to kilocy cles, The output of themodulatoroperates into another band-pass filter whose so that theoperator knows a pass band extends from 60. kilocycles to 64 kilocycles.

giving maximum gain'at 62.9 kilocycles. This intermediate frequencyamplifier works into the input of a demodulator havinga'crystal-c'ontrolled carrier frequency of 64 kilocycles. At the outputof this demodulator is a very narrow band-pass filter limiting thereceived frequencies to 1100 cycles 50 cycles. This band-pass filterworks into a final amplifier which has at its input an attenuatoradjustable in two steps.

In more detail we may now consider the circults indicated in Fig. 8.

With this leg rendered directional, the control of the'scanningoscillator 25 is manipulated until a definite indication is obtained.The control 25 may be calibrated to read values of the angle a directly.By then changing the indicator to work over the channel connected to legB a reading of the angle ,3 may be obtained on control 25 and these tworeadings may then be used to calculate the azimuth and colatitude anglesof the source of disturbance. This result may be Looking now at Fig. 9,thereis shown to the right a schematic representationof the glandthrough which the conductors of the submarine cable are brought into thetriangular prism; The numeral 45 designates the sheath of the cablewhich is secured by a water-tight 'fit to the gland member 46. Thevarious conductors of the cable are then played out and led throughproperly insulated holes in a bulkhead plate 41. to the, electricalnetworks of each leg.

Each leg constitutes a prism. The leg B contains a plurality of crystalelements 48, 49, and so on between each'of which-is a filter like thatshown in detail between the. crystals 48 and 49 and those indicated bythe rectangles 5|, 52 and so on. At the end of thecircuit there is aterminating network 53. By this arrangement a checked by taking areading of the angle A by control 21.

Each testing channel contains a series of clea trical networks as, apreliminary amplifier 28, a band-pass filter 29, a modulator 30, anotherbandpass filter 3|, an intermediate frequency amplifier 32, ademodulator 33, another band-pass filter 34, a final amplifier 35 and anattenuator 36.

There is also provided a pair of jacks 31 and 38 by means of which someindicating device orother network may be connected to the output of.each testing channel.

The alert channel 2| is less complicated in that no adjustments need bemade. There is a preliminary amplifier 39, a high-pass filter 40, alowpass filter 4|, a final amplifier 42and an attenuator 43., Y Apatching cord 44 is shown as available to make connection from any oneof the lacks shown to other apparatus as occasion and circumstances maydemand. I

The block diagram of this Fig. 7 comprises What may be termed a receiverand intheshort description to follow, certain values are given byprismatic effect is secured, that is the circuit functioning as areceiver is selectively responsive to different frequencies of incomingwaves in accordance with the angle of approach. this angle beingmeasured with reference .to the longitudinal axis of the device. Thereasons for such action are fully explained in my copending applicationshereinbefore referred to. It should also be noted that the crystals areof different dimensions. This is part of the arrangement by which thecrystals are arranged to be progressively more sensitive from the endstoward the middle of said crystal array for the purpose of suppressingsecondary lobes all morefully explained in my copending applications'hereinbefore referred to.

The leg A is somewhat more complicated, by

I the inclusion of a plurality of relays designated Relays RI, R3,R5,,R6, RI3, Rl4, Rl5, RIG, R39,

I R40, R41 and R48'are shown in one series circuit and the remainder inthe other.

Actually there are twenty-four relays in each circuit, certain of theinput signal; The of two v'oice frequency amassociated variable carrieroscillator of them being omitted from the drawings for sake ofclearness. With the relays in their normal positions as shown, each ofthe crystals 55, 51, 58 and so on is connected in multiple to theconductors 59 and 60 and thence to one winding of the transformer 6|.The other winding of the transformer 8| is connected to the coaxial lineindicated by the central conductor 52 and its sheath 53. In thisarrangement the leg A acts as a simple hydrophone and will respond toincoming waves over a wide range of frequencies.

When the conductors 56 and 55 are connected at the distant end to asource of current the relays will operate and convert the leg A to aprismatic device, including the various filters and networks to producethe desired result, the same as leg B shown in some detail and the leg Cindicated by the rectangle I58.

At the other end of the cable, shown in Fig. 10, the coaxial lineterminates in a jack 65 by which the conductors 62 and 63 may be patchedby the patching cord 66 to the terminals of. the testing channel. Thefirst circuit encountered thereafter is the input switching arrangement.This comprises two keys 61 and 68 both shown in their normal positions.Key 6! in its normal position leaves the extension of conductor 62 open.In one position key 61 extends this conductor to conductor 69 leading tothe alert channel and' in another position to conductor 10. Key '68 inone position connects the conductor I directly to the conductor leadingto the preliminary ampli fier, and in another position includes anattenuating pad consisting of a series resistance II and two shuntresistances I2 and I3 in this connection. It may be noted that inoperation the incoming signal is attenuated as much as possible at firstand that gradually and until a sufficient signal is received thisattenuation is reduced.

The preliminary amplifier is of conventional design and consistsessentially of a transformer I6 and three triodes I5, 15 and TI incascade.

Below the three preliminary amplifiers is shown a source of current foroperating the relays of the leg A. This consists of a source of directcurrent 18, the usual fuse I9, a milliammeter 8D and the usual smoothingnetwork. By means of key 8| this source of current may be connected tothe conductor 55 to operate the relays in leg A.

Also in Fig. there is shown a pentode 82 controlled by a crystal 83 in aconventional oscillator circuit for use as a test device. By means of apatching cord 84 this source of current may be connected into thenetwork at various convenient places to test the proper operationthereof.

In Fig. 11 the testing channel may first be traced through an output pad85 which is an attenuator controlled by a three position manuallyoperated switch 86 to introduce series and shunt resistances into thechannel in various obvlous combinations.

Next in line is a band-pass filter 81 indicated and of conventionaldesign. This filter is designed to pass only frequencies of 7.5kilocycles to kilocycles which are expected to be detected and which maybe modulated with the apparatus provided.

The next circuit network shown but not the next in line is the scanningoscillator generally included in the rectangle 88. This is an oscillatorof conventional design consisting generally of the three pentodes 89, 90and 9| and controlled by the variable condensers 92 and 93 by a commonshaft 94 moving a dial 95 by a fixed pointer 96. The range of thisoscillator is from 48 kilocycles to 56 kilocycles and is designed forcooperation with the range of thecrystai array prisms and the dial maybe calibrated, as before stated, to read the angles a, p or i. directly.The condensers 91 and 88 are permanently wired in the circuit aftertheir values have been selected to bring the mid-reading of thecalibrated dial 95 to the proper point.

The next circuit element in line is a modulator 99 of conventionaldesign shown in Fig. 12. By means of this network the incoming signal ismodulated with the output of the scanning oscillator to produce anintermediate frequency signal.

Following this is a band-pass filter I00 designed to pass the said givenfrequency signal derived from the modulation of the incoming signal.

This will be between 60 kilocycles and 64 kilocycles and may be variedby the movement of dial 95. The output of this band-pass filter is thenamplified by the intermediate frequency amplifier IDI consisting of fourpentodes I02, I03. I04, and I05 in an amplifier circuit which isdesigned to give a maximum output at 62.9 kilocycles so that byadjusting the dial 95 until the maximum signal has been attained theoperator will know that the signal has been modulated to exactly 62.9kilocycles.

Following the intermediate frequency amplifier in line and shown in Fig.13 there is a demodulator I06. This apparatus is served by a crystalcontrolled oscillator consisting essentially of the pentode I01, thecrystal I08 and the transformer I09, the output of which is coupled withthe demodulator I08 by the buffer amplifier H0. The output of theoscillator is 64 kilocycles so that the output of the demodulator is inthe neighborhood of 1,000 cycles. Actually the band-pass filter I l l isdesigned to pass a very narrow band of 11001-50 cycles so that thetuning of the receiver may be made very sharp. The output of thebandpass filter III is then passed through an attenuator I I2 and thendelivered to the final amplifier H3, consisting generally of pentode H4and triode H5. The output of the final amplifier is then delivered tothe switching arrangement of Fig. 14.

With plugs H6 and H1 in jacks H8 and H9 respectively and both keys I20and I2I operated, the operator may listen in with both ears on the alertchannel. Keys I22 and I23 when operated bridge the shock absorbingvaristors I24 and I25 across the earphones and may be removed when afaint signal is being received. The operator detecting the presence of adisturbing influence may then restore keys I20 and I2I and operate keysI26 and I2'I to listen in on the scanning channel for leg A. Aftermaking a satisfactory adjustment and taking a reading, he may thenswitch to another channel. It will be noted that with the arrangementprovided, he may listen in with one ear to any one channel and with theother car to another channel.

The elements in the alert channel are similar to the correspondingelements in the other channels with the exception of the high-passfilters I28 and I29 which together act to limit the frequency of theincoming signal to something between 1 kilocycle and 10 kilocycles.

Fig. 15 shows details of power supply networks for heating the filamentsof the various tubes and supplying the various potentials requiredthereby. No detailed description will be given as these are in manyrespects conventional circuits and the method of their operation is wellknown. They 15 consist generally of transformers and rectifying tubestogether with, the usual smoothing networks. Two signal lamps I30 and HIare provided to show the sources of current in operation.

What is claimed is:

1. A testing device for determining the direction of an incoming wavecomprising a triangular structure each leg of which comprises aprismatic responsive device consisting of a plurality of piezoelectriccrystals connected in an electrical network having phase shiftingnetwork elements between said crystals, whereby the response of any twoof said legs determines the direction of a line from said device to thesource of said incoming wave.

2. A locator for determining the direction of incoming compressionalwaves from a source of disturbance such as the propeller of a ship,comprising a triangular structure resting in a horizontal plane on thebed of the ocean, each leg of said structure comprising an array ofpiezoelectric crystals responsive to compressional waves transmittedthrough the sea water and an electrical network for rendering saidcrystal array prismatically responsive to said incoming frequency waves,whereby the response of any one leg of said device defines a planehaving a first line normal to the longitudinal axis of said leg and asecond line at right angles to said first line and at an angle to theaxis of said leg equal to the angle of approach of said incomingfrequency waves, and whereby the intersection of any two such planesdefined by two correspondinglegs defines a straight line between said;triangular structure and the said source of disturbance.

3. A locator for determining the direction of incoming frequency wavesfrom "a source of disturbance such as the propeller of a ship comprisinga triangular structure resting in a horizontal plane on the bed of theocean, each leg of said structure comprising an array of piezoelectriccrystals responsive to compressional waves transmitted through the seawater and an electrical network for rendering said crystal arrayprismatically responsive to said incoming frequency waves, saidelectrical network also being constructed and arranged to render saidcrystals progressively more sensitive from the ends toward the middle ofsaid array whereby secondary lobes whereby the response of any one legof said device deiines 'a plane having a first line normal to aresuppressed, whereby the response of any one i leg of said device definesa 'plane having a first line normal to the longitudinal axis of said legand a second line at right angles to said first line and at an angle tothe axis of said leg equal to the angle of approach of said incomingfrequency waves, and whereby the intersection of any two such planesdefined by two corresponding legs defines a, straight line between saidtriangular structure and the said source of disturbance.

4. A submarine detecting and locating device for determining thepresence and the direction of incoming compressional waves from a sourceof disturbancesuch as the propeller of a' ship comprising an array ofpiezoelectric crystals, a network of .filters,

a plurality of relays, a circuit arrangement of said crystals controlledby said relays in one position thereof, wherein said crystals areresponsive to a broad band of frequencies of incoming waves, analternative, circuit arrangement of said crystals and said filterscontrolled by said relays in another position thereof, wherein saidcrystals are prismatically. and selectively responsive to narrow bandsof frequencies of incoming waves, whereby the response of said device insaid alternative arrangement defines a plane having a first line normalto the longitudinal axis of a locating means.

5. A submarine detecting and locating'device for determining thepresence and the directional incoming compressional waves from a-sourceoi disturbance such as the propeller of'a snip comprising atrianguiarstructure restingin a hori--' zontal plane on the bed of theocean, each leg of said structure comprising an array of piezoelectriccrystals responsive to compressional waves transmitted through the seawater-and an electrical network for rendering said crystal arrayprismatically responsive to said incoming waves,

the longitudinal axis of said leg and a second line at right angles tosaid first line and at an.

angle to the axis of said leg equal to the angle of approach of saidincoming waves, and whereby the intersection of any two such planesdefined by two corresponding legs defines a, straight line between saidtriangular structure and the said.

source of disturbance, one of said legs having in addition a pluralityof relays, an electrical network controlled by said relays in analternative position for rendering the said array of crystals thereinbroadly and non-directionally responsive to said incoming waves, andmeans for'controlli'ng said relays. v

6. A locator for determining the direction of incoming compressionalwaves from a source of disturbance such as the propeller of a ship,comprising a triangular structure resting in a horizontal plane on thebed of the ocean, each leg of said structure comprising an array ofpiezoelectric crystals responsive to compressional wavesthe sea waterand an .electransmitted through trical network for rendering saidcrystal array prismatlcally responsive to said incoming frequency waves,whereby the response of any one leg of said device dennes a plane havinga first line normal to the longitudinal axis of said leg and a secondline at right angles to said iirst line and at an angle to the axis ofsaid leg equal to the angle or approach of sa d incoming irequencywaves, and whereby the intersection of any two sucn planes defined bytwo corresponding legs defines a straight line between said triangularstructure and the saia source or disturbance, a receiver for measuringthe response of said legs, and a submarine cable connecting saidtriangular structure and said receiver.

7. A locator ior determining the direction of incoming compressionalwaves from a source of disturbance such as the propeller of a ship,comprising a triangular structure resting in a horizontal plane on thebed of the ocean, each leg of said structure comprising an array ofpiezoelectric crystals responsive to compressional waves transmittedthrough the sea water and an electrical network for rendering saidcrystal array prismatically responsive to said incoming frequency waves,whereby theresponse of any one leg of said device defines a plane havinga first line normal to the longitudinal axis of said leg and a secondline at right angles to said first line and at an angle to the axis ofsaidleg equal to the angle of approach of said incoming frequency waves,and whereby the intersection of any two such planes defined by twocorresponding legs defines a straight line between said triangularstructure and the said source of disturbance, a receiver having atesting channel corresponding to each leg of said device for measuringthe response of said corresponding leg, and a submarine cable connectingsaid triangular structure and said receiver.

8. A submarine detecting and locating device for determining thepresence and the direction of incoming compressional waves from a.source of disturbance such as the propeller of a ship comprising atriangular structure resting in a horizontal plane on the bed of theocean, each leg of said structure comprising an array of piezoelectriccrystals responsive to compressional waves transmitted throughgthe seawater and an electrical network for rendering said crystal arrayprismatically responsive to said incoming waves, whereby the response ofany one leg of said device defines a plane having a longitudinal axis ofsaid leg and a second line at right angles to said first line and at anangle to the axis of said leg equal to the angle of approach of saidincoming waves, and whereby the intersection of any two such planesdefined by two corresponding legs defines a straight line between saidtriangular structure and the said source of disturbance, one of additiona plurality of relays, an electrical network controlled by said relaysin an alternative position for rendering the said array of crystalstherein broadly and non-directionally responsive to said incoming waves,means said relays, a receiver having four testing channels comprising analert channel for detecting the response of said one leg when convertedto a broad non-directional responsive device and three other channelsone each corresponding to a leg of said triangular device for measuringthe angular response thereof, and a submarine cable connecting saidtriangular structure and said receiver.

9. A testing device for determining the direction of an incoming signalin the form of compressional waves of a broad band of frequencies,

first line normal to the said legs having in for controlling comprisinga plurality of responsive devices, each said responsive device beingselectively responsive to a single frequency of said broad band offrequencies in accordance with the angle of approach of said signal tosaid responsive'device, said plurality of responsive devices beinggeometrically arranged with respect to each other in a knownconfiguration whereby the response of at least two of said devices willprovidesufiicient data for mathematically computing the direction ofsaid incoming signal. I

10. A testing device for determining the direction of an incoming signalin the form of compressional waves of a broad band of frequencies,comprising a plurality of responsive devices, each said responsivedevice being selectively responsive to a single frequency of said broadband of frequencies in accordance with the angle of approach of saidsignal to said responsive device, said plurality of devices beinggeometrically arranged in a horizontal plane with respect to each otherin a known configuration and the orientation of said testing device withrespect to a known reference line being known, whereby the se'ectiveresponse of at least two of said responsive de-' vices'will providesufilcient data for mathematically computing the direction of saidincoming signal.

WARREN P. MASON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,169,304 Tournier Aug. 15, 19391,378,960 Horton May 24, 1921 1,411,948 Williams Apr. 4, 1922 FOREIGNPATENTS Number Country Date 279,878 Great Britain Mar. 8, 1928

